Optimise Non-Capturing Lambdas

[iamrecursion]

Summary

In the current Enso interpreter all lambdas will capture their outer scope, materialising the parent stack frame even if they don't need to. We can optimise this by not materialising the frame unless specifically required to by the variables captured in the lambda.

Specification

• Rework the implementation of lambdas such that they do not materialise their parent frame unless necessary.

Acceptance Criteria & Test Cases

• The above optimisation has been made.
• It results in performance improvements.

[kustosz]

I cannot satisfy the second acceptance criterion – I cannot find a single benchmark that has room for improvement. I've tried refactoring the current benchmarks to take lambdas instead of just performing operations like addition. They have exactly the same scores. So I'm not implementing this – there's no point maintaining additional code when we don't have a tangible reason to. Moving this task to the icebox – maybe it will prove useful at a later stage.